External rotor motor



June 29, 1954 K. REICH ETAL EXTERNAL RoToR MoToR 3 Sheets-Sheet 1 Filed Aug. 3. 1949 June 29,1954 K. REICH TAL 2,682,617

EXTERNAL ROTOR MOTOR Filed Aug. 3, 1949 5 Sheets-Sheet 2 June 29, 1954 K, RElCH ET AL 2,682,617

EXTERNAL ROTOR MOTOR Filed Aug. 3, 1949 3 Sheets-Sheet 3 lnnnlww"wnmmm...wn.......,..... "um" "nm" Patented June 29, 1954 EXTERNAL ROTOR MOTOR Kurt Reich, Nurtingen-Zizishausen, and Gustav Walliser, Reutlingen-Betzingen, Germany, assignors to Firma Karl M. Reich, Nurtingen (Wurttemberg), Germany Application August 3, 1949, Serial N0. 108,393

Claims priority, application Germany October 1, 1948 6 Claims. l

This invention relates to an external rotor motor, and in particular the invention refers to the use of the external rotor motor with a Wood planing machine.

With known external rotor motors, which are used With wood working machines, the outer rotating short-circuited rotor carries a special drum on which the tools are arranged.

The invention has for its object a simplication and improvement of such wood working machines in particular of wood planing machines with an external rotor motor.

This simplication and improvement consists in the main in dispensing with the drum of the external rotor motor while the tools and their means of attachment are arranged directly on the cylinder which is formed by the rotor.

Although wood planing motors, the outer rotating rotor of which has a drum which carries the tools, have for long been known, the idea has not yet occurred of dispensing with the drum. Probably the injurious effect of eddy currents which occur was feared. Such eddy currents, however, do not take place with the external rotor motor according to the invention. By dispensing with aseparate drum surrounding the rotor and which takes the tools, the production of an external rotor motor is extraordinarily simplified andl cheapened. Furthermore, any fears with respect to the resistance of the drum weakened by the arrangement of the tools is obviated since according to the invention such a drum is not used at all. Furthermore, the construction according to the invention presents the advantage that the diameter of the circle upon which the cutting edges of the tools lie is reduced. In this way, with the same torque, the circumferential force is greater. Conversely, in consequence of the construction according to the invention, the cut-out part in the base plate becomes smaller through which the tools protrude in working.

An effort is made to keep this cut-out part as small as possible in order to obviate accidents. The advantageous reduction of the cut-out part in the base plate results from the reduction already mentioned of the. diameter of the circle upon which the cutting edges of the tools lie. Furthermore, there results by dispensing with a separate drum serving as tool carrier for the rotor, eicient cooling of the rotor plates and this acts beneficially on the efficiency and output. The object of the invention is shown by way of example in the drawing, in which:

Figure 1 is the planing machine shown partly `in longitudinal section on the line I-I of Figure 2 and partly in elevation, without table;

Figure 2 is a cross-section of the rotor without bearing bracket, on the line II-II of Figure 1;

Figure 3 is a longitudinal section of the rotor without bearing bracket on the line III-III of Figure 2;

Figure 4 is a longitudinal section somewhat corresponding to the line III-III of Figure 2, of a second embodiment;

Figure 5 is a longitudinal section partially corresponding to the line V-V of Figure 2 of the embodiment according to Figure 4;

Figure 6 is a longitudinal section, corresponding to the line III- III of Figure 2 of a third embodiment; and

Figure 7 is a longitudinal section, corresponding to the .line III-III of Figure 2, of a fourth embodiment.

In the embodiment according to Figures 1-3, the rotor of the external rotor motor represented consists of a packet of plates I which forms a cylinder 2l. The plates I have the form of annular discs as shown by Figure 2.

The packet of plates or the cylinder 2l are held together by rings 2 which are arranged on the two side faces of the cylinder 2| and which have the same cross-section as the plates I. Preferably, however, the rings 2 have a diameter which is from 1 to 2 mm. less than that of the plates I, so that the tools for the clamping together of the cylinder 2| can be arranged on the projecting edge 3 of the cylinder 2I. The cylinder 2I and the rings 2 are held together by rods 5 or by a metallic press mass, which both consist of a particularly good conducting substance and which pass through holes 4 of the rings 2 and of the cylinder 2 I. In the use of rods 5 these are rivetted by their ends in the rings 2.

In the case of the use of press masses the rings 2 and the mass lling the holes 4 consist of a casting.

The end faces of the rotor are covered by bearing brackets or plates 6. These are held'together by means of anchoring bolts 8 which pass through holes 20 provided in the rings 2 and in the cylinder 2 I. The bearing brackets or plates are carried by means of ball bearings 22 on the stationary shaft I, so that the whole rotor is carried in this way. Furthermore, the bearing brackets or plates 6 are centered in the rings 2 which cover the end faces of the cylinder ,2| by means of a cylindrical addition I6 which is located within the circle of the anchoring bolts. The stationary pole winding 9 is arranged on the stationary shaft l.

According to the invention, the arrangement is now so contrived that the tools I I are xed on the cylinder 2| by means of tensioning strips I2 and by means of screws I3. The tools II are distributed symmetrically over the periphery of the rotor. In the example illustrated, two tools I I are provided which are diametrically opposite to each other. The tools II and the tensioning strips I2 extend in the longitudinal direction not only over the cylinder 2l but also over the rings 2 and the bearing plates E, so that the whole width of the rotor is utilised. The tensioning strips I2 are so shaped and let into the cylinder 2l, the rings 2 and the bearing plates 6, that they represent segments of the cylinder which forms the rotor. The screws I3 are anchored in the cylinder 2| and the bearing plates 6.

Cut-out parts or recesses I0, which run in the longitudinal direction, that is on contour lines of the cylinder 2 I are provided in the cylinder 2 I, the rings 2 and the bearing plates 6 corresponding' to the arrangement of the tools I I. The tools I I, in the example represented by planing or surfacn ing knives, are arranged in these recesses ill. The tensioning` strips I2 represent segments of the cylinder which is formed by the rotor, so that, apart from the projecting cutting edges of the tools I I and the channels I4 provided under these cutting edges, the jacket of the rotor presents a flat surface. The arrangement is here so contrived that the screws I3 are so arranged between the holes Ii, that the rods 5 or the mass which fill the holes li, cannot be cut into. This has for its object not to unfavourably influence the currents which flow through the rods 5 or the mass which is in the holes t. Both, that is the rods or the mass, consist of a substance which is a particularly good conductor.

The supporting surfaces 24 for the tools I I are, according to the invention, arranged obliquely to the supporting surfaces of the tensioning strips I2, so that there is given an advantageous tensioning angle, which should amount to about 30415). in this way, the life of the tools is increased. With external rotor motors already known designed as wood planing machines and in which the tools are arranged in a separate drum surrounding the external rotor, the tools are tensioned in parallel to the supporting or bearing surfaces of the tensioning strips, so that there arises a greater and consequently less favourable tensioning angle.

The tensioning strips I2 are provided with two fitting strips I'I running on their inner edges, of which one rests on the base surface of the cut-out part Iii and the other on the front part of the tool i I. By this construction, the tensioning force is favourably distributed. In particular a pressure is exerted on the front part of the tool II. In order to impart a greater strength to the rotor and in particular to prevent in any case a shifting of the rotor blades i in their planes with respect to each other, the bottom surface of each cut-out part or recess is provided with a groove 23 in which one adjusting or fitting strip I1 is seated, this being raised with respect to the other fitting strip Il'.

In cases where the possibility might arise that the rotor blades are warped when the screws I3 are screwed directly into the rotor blade packet, further embodiments of the object of the invene tion are provided. The consequences of the warping or distortion of the rotor blades I would be insufficient firm tensioning of the cutters or knives II, the blocking-up of the supporting surface of the knife cutting edges with shavings and the bending of the planing knives I I.

With the embodiment according to Figures 4 f packet inside the rings 2.

and 5, the rotor also consists of a packet of plates I having the form of annular discs as shown by Figure 2. The plate packet is held together on the end surfaces by rings 2 which have the same shape as the plates I. The plates I and the rings 2 are held together by rods which pass through holes It of the rings 2 and of the plate packet, or as represented in Figure 5, by a metallic press mass which fills the holes Ii and consists of a casting with the rings 2. With this embodiment, there is provided a ring Iii preferably consisting of steel and which is arranged in the centre of the plate packet. In so far as screws I3 are provided within the range of the rotor plates I, they are now not anchored in the plate packet itself but are screwed into the ring I8. Otherwise the tensioning strips I2 are still fixed by screws which are anchored in the bearing brackets or plates 6 (not shown in Figures 4 and 5).

Instead of one ring I8, a plurality of rings I8 may be provided. These can be uniformly distributed over the cylinder 2 I. In the embodiment according to Figure 6, two rings I3 are provided which are arranged on the end faces of the plate The screws I3 are, in this case, screwed into the steel rings I8.

Both with the embodiment according to Figures 'i and 5 as also with the embodiment according to Figure 6, the rings I8 have the holes 4 for the passage of the rod E of the metallic press mass and the holes 2G for the anchoring screws 8.

Figure '7 shows a further embodiment in which the whole plate packet is replaced by a solid steel ring is which is located between the rings 2. In this ring screws I3 for the fastening of the tools i I and of the tensioning strips I2 are screwed directiy. The solid steel ring I9 of the length of the plate packet is also provided with holes 4 for the passage of rods 5 or as shown in Figure 7, of metallic press masses which with the rings 2 consist of a casting. Furthermore, the solid steel ring i9 has bores or holes 20 for the anchoring screws 8.

We claim:

1. An external rotor motor particularly for a wood planing machine, comprising a stationary shaft, a stationary pole winding arranged on said shaft, a pair of bearing means mounted in spaced relation from one another on said shaft and arranged adjacent each side of the stationary pole winding, two bearing plates each carried by its respective bearing means, a plurality of annular disc laminations arranged to form a cylindrical core concentrically surrounding the stationary pole winding, two rings arranged on the two side faces of the core, short circuitng bars joining the two rings, the core and the rings being arranged between the bearing plates, means for holding the core, the rings and the bearing plates together in axial direction to form an outer rotating short-circuited rotor, at least one wood working tool housed in a recess in the outer surface of the rotor core, and fastening means for the tool including a tensioning strip, the tool and the tensioning strip being arranged in a recess provided longitudinally on the surface of the rotor core, the cutting edge of the tool projecting beyond the surface of the rotor core, and the tensioning strip being shaped as a segment of the rotor core, whereby the jacket of the rotor provides substantially a flat surface apart from the projecting cutting edges of the tools and the longitudinal channels provided under said cutting edges.

2. An external rotor motor particularly for a wood planing machine, comprising a stationary shaft, a stationary pole winding arranged on said shaft, a pair of bearing means mounted in spaced relation from one another on said shaft and arranged adjacent each side of the stationary pole Winding, two bearing plates each carried by its respective bearing means, a plurality of annular disc laminations arranged to form a cylindrical core concentrically surrounding the stationary pole winding, two rings arranged on the two side faces of the core, short circuiting bars joining the two rings, the core and the rings being arranged between the bearing plates, means for holding the core, the rings and the bearing plates together in axial direction to form an outer rotating short-circuited rotor, a plurality of wood working tools symmetrically arranged around the periphery of the rotor core and adapted to be housed in recesses of the rotor core, and fastening means for each tool including a tensioning strip, said tools and tensioning strips being arranged in pairs in recesses provided in longitudinal direction on the surface of the rotor core, the cutting edges of the tools projecting beyond the surface of the rotor core, and the tensioning strips being shaped as segments of the rotor core, whereby the jacket of the rotor provides a substantially flat surface apart from the projecting cutting edges of the tools and the longitudinal channels under the cutting edges.

3. An external rotor motor according to claim 2, in which the rotor has bearing surfaces for the tools arranged obliquely to the tensioning strips and the fastening means for each tool include at least one screw secured in the rotor core and countersunk in its tensioning strip.

4. An external rotor motor according to claim 2, in which the rotor core is composed of a plurality of parts, and in which members are provided carried through holes in the parts parallel to the axis of the rotor core, said screws being so arranged between the holes that they do not intersect said holes. f

5. An external rotor motor according to claim 2, in which each tensioning strip is provided with two adjusting strips on their inner edges of which one bears on the rotor core and the other on the tool.

6. An external rotor motor according to claim 2, in which each tensioning strip is provided with two adjusting strips on their inner edges of which one bears on the rotor core and the other on the tool, and in which the rotor core is provided with a recess for each tensioning strip with a groove in the bottom of each recess for the strip which bears on the rotor core.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,420,774 Stainbrook June 27, 1922 1,432,7 92 Schimmel Oct. 24, 1922 1,620,847 Whisler Mar. 15, 1927 1,980,056 Hedeby NOV. 6, 1934 2,041,442 Stinsman May 6, 1936 FOREIGN PATENTS Number Country Date 199,324 Great Britain June 21, 1923 

